The experiments proposed here will be carried out as part of a general investigation into the neural mechanisms underlying ethanols disruptive effect on cognitive functions. In particular, selective attention to a sensory stimulus in the presence of distraction is known to be a cognitive skill which is markedly disturbed during intoxication. The PI has developed a relatively simple neurophysiological model for selective sensory processing in the cerebral cortex and is currently using this model in assessments of the effects of acute ethanol intoxication. This model involves recording single units in the primary somatosensory (SI) cortex of rats. Computer techniques are used to measure the gating of cutaneous sensory transmission from the forepaw to these cells during, and in correlation with, link movements to touch the ground in locomotion. Normally, inhibitory controls only allow this sensory information to reach certain cortical cells during precise phases of the step cycle. Ethanol, among other things, appears to reduce or abolish these inhibitory controls in a dose-dependent fashion and thus allow sensory inputs to reach cortical cells in an unfiltered fashion. The experiments proposed here will: 1) investigate these findings in the SI cortex more thoroughly, 2) utilize the Preferring (P) and Non-preferring (NP) rat strains of Li in similar experiments, 3) investigate the possibility that ethanols reduction of inhibitory gating controls may result from disruption of activity in the adjacent motor cortex (one possible source of the gating bias signal) or motor cortical afferents, and 4) develop an operantly controlled behavioral paradigm for "passive" selective attention in which sensory stimuli are made "significant" by pairing it with a reward.